The improvements in the hardware and software used on computers lead to rapid developments in the presentation of information. Visual, audio and haptic information can each be presented using its own appropriate hardware and associated software. Visual rendering is enabled by the developments in the field of computer graphics. Rendering can be based on geometric and non-geometric methods. Geometric surface rendering is based on the use of polygons, implicit and parametric surfaces and constructive solid geometry. Non-geometric (non-surface) rendering of objects includes the volumetric method and methods based on particle description. One technique used for non-geometric rendering is the ray-tracing method. In the ray-tracing technique, an image is generated by tracing the path of light through the pixels in an image plane. As the light rays are subject to laws of optics, they are altered due to reflections from surfaces that make up the virtual objects as well as transmissions through semi-transparent surfaces.